Mahlon randolpfl



(No Model.)

M. RANDOLPH.

MECHANICAL TELEPHONE, No. 307,800. Patented Nov. 11, 1884.

n. PETERS PhMn-Ldhngmphur. Waihmgmn. D. c.

UNITED STATES PATENT OFFICE.

MAHLON RANDOLPH, OF NEW YORK, N. Y., ASSIGNOB TO THE UNIVERSAL TELEPHONE COMPANY, OF SAME PLACE.

MECHANICAL TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 307,800, dated November 11, 1884.

Application filed January 28, 1884. (No model.)

To all whom it may concern:

Be it known that I, MAHLoN RANDOLPH, of the city, county, and State of New York, have invented a new and useful Improvement 5 in Mechanical Telephones; and I hereby declare the following to be a full and clear description of the same.

The object of this invention is to construct a mechanical telephone in such a substantial manner and with such clear transmittive power as to render a mechanical telephone adapted to much longer distances and to much more general use than any mechanical tele phone heretofore made.

The details of the telephone I have devised are clearly described in the subjoined specification, and illustrated in the accompanying drawings, of which- Figurel is afront view of one ofmy improved telephones. Fig. 2 is a vertical sectional elevation of one of my said improved telephones, taken on the line or w of Fig. I.

The case A of the telephone is constructed of any suitable material, and is made cylindrical, polygonal, rectangular, or in any other convenient or suitable form. The diaphragm B is drawn tightly over the front edges of the case A, and it held in position at said edges by any suitable means or devices.

In all mechanical telephones it is requisite that the diaphragm must be thin, strong, and in a high state of tension. To meet these requirements I make the diaphragm B of very fine bolting-cloth. It is obviously possible to use any thin textile goodsas, forinstance, silk with other mechanism, or other materials such as fine skins 1 india-rubber goodsmay be used; but I prefer, for the best results, to use the bolting-cloth, as being lighter, stronger, more sensitive, and in every way better adapted to the purpose than any other known or hitherto-used material. The line-wire Gis connected with the diaphragm by numerous short diverging wires, 0, as shown in Fig. 2,

| and these wires are secured to the diaphragm 4 5 by means of thin metallic clamping or anchorage plates 1) b, placed on the opposite sides of the diaphragm, either in the form of annular plates, as shown in Fig. 1, or in the form ofsinallwashers. These clamping-plates are best made of German silver; but thin brass, copper, or other material will answer the purpose.

By the use of the thin diaphragm above described and the clamping or anchorage plates 5 5 for holding the wire taut without tearing or injuring the diaphragm a very durable and highlysensitive telephone is produced.

The bolting-cloth diaphragm is coated on one or both its sides with a thin and elastic siz- 6o ing-something like india-rubber cementso as to fill up the pores of the goods,while at the same time leaving it perfectly flexible.

From the foregoing it will be apparent that a telephone constructed as herein described is both sensitive and positive in operation, and capable of responding to and imparting the most minute vibrations of the line-wire O.

D, Fig. 2, is a case designed to receive or transmit the vibrations for or from the diaphragm B.

The case D, or the construction of the diaphragm B from bolting-cloth or its equivalent, coated or otherwise treated, forms no the subject-matter of a separate application for Letters Patent.

Having fully described my invention, I claiin The diaphragm B, provided with metallic 80 anchorage or clamping plates 6 b", and com bined with the conneeting-wires c, substan tially as and for the purpose set forth.

llI. RANDOLPH.

\Vitnesses:

IV. I. DoUonTY, G. LINELL.

part of the present invention, but will form 

